1. Field of the Invention
The present invention relates generally to systems for transporting payloads on aircraft. More specifically, the invention relates to a system for attaching and selectively releasing multiple cargo payloads which are transported by being suspended beneath an aircraft such as a helicopter.
2. Relevant Technology
Aircraft such as helicopters have long been used to deliver payloads of different size and shape. Traditionally, a cable is suspended from a helicopter with a hook attached to one end of the cable. By attaching the hook to a payload, the helicopter is able to transport the payload to a desired location. Suspending the payload beneath a helicopter permits the helicopter to transport oversized cargo, such as a jeep or other large hardware.
Furthermore, the helicopter is able to deliver the payload to unique and specific locations, such as on top of a building or in rugged terrain, where an airplane could not land. In addition, the use of a suspended cable permits the helicopter to deliver or recive cargo without actually having to land. By lowering the cable, a receiving party can remove or attach a payload to the hook. This is most beneficial with regard to emergency rescues and in delivering payloads in congested areas.
Although there are numerous benefits in using a conventional hook and cable assembly to deliver a payload suspended beneath a helicopter, several shortcomings are also found. For example, using a single cable and hook assembly typically permits the transport of only a single payload per flight. Such an assembly necessitates numerous flights, costing both time and money, to deliver multiple payloads which cannot simultaneously be attached to a single hook.
Furthermore, to remove a payload from a conventional hook and cable assembly, either the helicopter must land or the payload must be lowered to the ground and manually removed from the hook. Such procedures require both a certain amount of time and the necessity of a receiving party at the unloading location to remove the payload. The necessity of a receiving party to remove the payload is detrimental in an emergency situation where it is preferable to jettison the payload during flight or where it is desirable to release a payload at a location where there is no receiving party.
In an attempt to alleviate these problems, carrousel hook systems have been made. The carrousel hook systems comprise a frame having a plurality of hooks attached thereto. The frame is suspended from a helicopter by a support cable. Likewise, an electrical cable extends from the helicopter to each of the hooks. By triggering a switch within the helicopter, the hooks can be consecutively opened, thereby releasing the attached loads.
Several problems or shortcomings, however, have also been encountered with carrousel hook systems. Forces such as the wind and movement of the aircraft can result in rotation of the carrousel frame which in turn applies a torsional force on the support cables and the helicopter. Such a force can damage the cables and the connection to the helicopter. Likewise, the torsional force can affect the navigation ability of the helicopter.
Conventional carrousel systems are also designed to carry multiple payloads so that the frame is evenly balanced. When only a single load is being carried, the unbalanced force of the payload can produce detrimental stresses on the frame.
Carrousel systems also have the drawback in that the hooks can only be activated consecutively and not selectively. That is, carrousel hooks can only be opened in sequential order. At times, it is desirable to be able to selectively open any desired hook.
Finally, an additional problem with some carrousel systems is that they are difficult to transport other than below a helicopter. That is, carrousel systems are often too big to fit within a helicopter or in the bed of a pickup truck. Since helicopters travel slower when the carrousel system is suspended below, it is desirable to be able to store the system within the helicopter when it is not required.
Accordingly, there is a need for an improved system for transporting cargo suspended from an aircraft that overcomes or avoids the above problems.